I'd imagine this is going to depend greatly on what you have to work with. As a general rule, lowest ISO insures least noise, and stopping down to around f/8 or f/11 is the sharpest setting for lenses. This will probably require using a tripod, or most likely flash unless you're shooting outdoors under harsh conditions. Each way requires special techniques to soften shadows, or avoid red eye. Google can render some great information, as a start, you might like to see this article on informal portraiture:
http://digital-photography-school.com/blog/10-ways-to-take-stunning-portraits/There's other links on the site which should go through basics, such as using a flash and I'm sure others here will have suggestions too.
Good luck, and enjoy.
Edit: oh, forgot to mention... if shooting individuals, you'll probably want to isolate them from the background, so shooting with an open f/stop is required. Basically, like all type shots, you need to determine how to shoot each shot as you go. There's really no hard set rules, unless you're trying to duplicate stock portraiture?